Vaayu. As Vaayu lives everywhere, in the Bhuvah or in Antariksh, Vasu also live everywhere.
MBH says that there are 8 Vasu - Aaditya (Sun), Chandra (Moon), Varun (sky), Arun (dawn), Ahah (day), Raatri (night), Sandhyaa (twilight) and Dharm. [These Vasu are different from the known Vasu or Vasu Devtaa]
[Mahaanirvaan Tantra, p 97]

Earth's Connection with Vasu?
As per Hindu concept, the Earth is stabilized by 8 Vasu or 8 directions such as East (Poorv), West (Pashchim), North (Uttar), South (Dakshin), North-East corner (Eeshaan), East-South (Aagneya), South-West (Nairutt) and North-West (Vaayavya) and each direction is controlled by a specific Devtaa.

When the solar radiation reaches the Earth and spread through its intensity, it varies from direction to direction, place to place based on the Earth's position in the zodiac belt, rotation, inclination and other geographical and metrological factors. So the major variation of the solar intensity from direction to direction is considered as a factor, named as Vasu. In toto the point of generation of solar energy is Aaditya, the transmittance of radiation is Rudra and the point of recipient and implementation is named as Vasu, based on two universal factors - time and space, are considered as 31 Pitri persons. Since each one of the 31 Pitri has its individuality from position and functional point of view, each one is considered as a separate entity, irrespective of the radiation generated from the same Sun.